The volatile oil was extracted from Curcuma longa and Turmeric oleoresin by Soxhelt method with petroleum ether.All the volatile oil was analyzed of chemical component by the method of GC-MS,the relative contents of these compounds were calculated using square peaks to normalization.On the volatile oil of Curcuma longa 35 peaks were separated and 21 compounds were identified,which accounted for 89.10%,the main chemical constituents was (-)-Zingiberene(22.12%),β-Sesquiphellandrene(15.24%),α-Turmerone (11.30%),β-Turmerone (8.87%),Ar-turmerone(8.20%),but on the volatile oil of Turmeric oleoresin 32 peaks were separated,of which 21 compounds were identified,which accounted for 90.12% the main chemical constituents was (-)-Zingiberene(23.92%),β-Sesquiphellandrene(15.73%),Ar-turmerone(12.89%),β-Turmerone(10.85%).
Although there was a strong steric effect,isopentenyl and geranyl moieties were successfully introduced into C3 position in flavone skeleton so as to synthesize the 3-isopentenyl flavone and 3-geranyl flavone under two cyclization conditions（AcOH/HCl and concentrated H 2 SO 4 /MeOH） in this report.It was found that the optimum cyclization conditions for 3-isopentenyl flavone and 3-geranyl flavone were,respectively,AcOH/HCl and H 2 SO 4 /MeOH.Furthermore,the donating electron ability is in the sequence 3-geranyl flavone3-isopentenyl flavone according to the density functional theory（DFT） calculations,suggesting the longer alkyl chain at 3-position would be more favorable for enhancing the donating electron ability.The present synthetic routes might reveal potential applicability in our continued studies on the total syntheses of other natural 3-alkyl flavonoids.
